Extreme pressure lubrication



Patented Oct. 25, 1938 PATENT oFFica EXTREME PRESSURE wnarca'rrou 7 TroyLee Cantrell and James Otho Turner, Lansdowne, Pa., assignors to GulfOil Corporation, Pittsburgh, Pa., a corporation of Pennsylvania NoDrawing. Application April 24, 1937, Serial No. 138,860

14 Claims.

This invention relates to improved lubricating oils and in particular tolubricating oil compositions containing an oil-soluble agent or agentseffective to impart so called extreme-pressure characteristics thereto,said agent being an alkylphenyl oxy-ether of 2:4-dinitrobenzene, andsaid compositions also having certain additional advantages as set forthhereinbelow.

This application is a continuation-in-part of; our prior application,Serial No. 98,828, filed Aus' gust 31, 1936. That application relates todie manufacture of ortho-substituted aryl ethers, including ethers of2:4-dinitrobenzene. As disclosed in that application, such ortho-nitro-15 phenyl ethers generally are miscible with mineral lubricating oils,and when dissolved in such oils give improved lubricants.

This is also true of the ethers of 2:4-dinitrobenzene made by thegeneral methods of our prior application, particularly the alkyl-phenyloxy-ethers. In another continuation of Serial No. 98,828, filedsimultaneously with the present application, we describe and claimalkyl-phenyl oxy-ethers of 2:4-dinitrobenzene and improved methods ofmaking such ethers, namely, application Serial No. 138,858. Thealky-phenyl ethers there disclosed are useful for various purposes.

The present application is directed to improving mineral lubricatingoils and lubricants containing such oils, with these oil-solubleallqlphenyl oxy-ethers, particularly ortho-alkyl-phenyl ethers of2:4-nitrobenzene, as the improvement agent in such lubricatingcompositions. By the present invention, improved lubrication isobtained, particularly in lubricating metal bearing surfaces at highpressures, speeds and temperatures.

Despite the many technical advances which 7,

have been made in the arts of refinin'gand fap plying lubricating oils,modern lubricating oils about through constant attempts on the partofengineers to improve engines and machines with respect to compactness,speed, power and acceleration. In order to provide satisfactorylubrication for modern designs and keep pace with new mechanicalimprovements in design, it is necessary to provide lubricatingcompositions having improved lubricating value as compared. withstraight lubricating oils and which will give satisfactory service underdrastic lubricating con- 5 ditions under which straight mineral oilswould ,fail to perform satisfactorily.

Thus, considerable attention is being paid to the development oflubricating oil compositions which are capable of giving satisfactoryservice 10 under high pressures, such compositions being generally knownin the art as extreme-pressure or "EP lubricants. A number of materialshave been developed which, when added to hydrocarbon oil, materiallyincrease the ex- 15 treme-pressure properties of the oil; the resultantcompositions give more acceptable service under higher pressures betweenbearing surfaces than is true of the untreated oil. Some of these agentsare extremely effective but too expensive for general use, and others,while contributing satisfactory extreme-pressure properties to the oil,are unsatisfactory for other reasons. A primary requisite of anyimprovement agent is good oil-solubility under service and marketing 25conditions; such agents when added to hydrocarbon oils in small amountsshould not impart to the resulting compositions a hazy or cloudyappearance, should not deposit out when the compositions are stored andpackaged prior 30 to sale, and should not attack metal surfaces ofcontainers used for packaging and storing them. The improvement agentshould also be highly effective per unit concentration in thelubricating oil compositions; otherwise it would be neces- 35 sary toadd such an amount of the improvement agent as to substantially modifymany of the desirable physical properties of the lubricating oil itself.Such oils have been carefully refined to meet exacting specifications,and if it 40 is necessary to incorporate therein relatively largeamounts of some agent or agents differing in physical properties fromthe oil itself, the resulting compositions may prove unsatisfactory forthe purposes for which the lubricating oils were prepared. In general itis desirable that any improvement agent should be efiective atconcentrations not exceeding 1 or 2 per cent, or at the most 5 per cent,by weight of the lubri- 50 cating oil.

'For many purposes it is not necessary to increase the load-carryingproperties of lubricating oils to several times the load-carryingproperties of the original oils. For example, in the pendingapplication, Serial No. 99,488, there is disclosed a process ofmanufacturing an antioxidant wherein a phenol is mixed with from 1 to 10per cent of sulfuric acid having a strength of 60 to 100 per cent, oreven fuming sulfuric acid, and an olefin or a mixture of olefins ispassed, preferably in the vapcrous or gaseous phase, through the liquidmixture until the phenol undergoing reaction has gained in weight from100 to 200 per cent, or thereabouts, followed by washing the product soobtained with water and with caustic soda solution, the concentration ofwhich does not exceed 15 per cent. Various phenols may be employed, forexample, phenol (CsHsOH) itself, the three cresols and certain xylenols,[(H3C)2-CsH3-OH] and crude cresylic acids may be employed. Pyridines, ifpresent, should be removed by conventional methods, such as washing withacid or by distillation.

As olefinic starting materials, there may be employed individual olefinsthemselves, mixtures of olefins, or mixtures of olefinic andnon-olefinic material. By wayof example, the olefinic starting materialmay be butylenes, amylenes, refinery gases containing normally gaseousole fins (propylene, butylene) in varying amounts,-

and cracked distillates or other relatively lowboiling hydrocarbonmixtures containing normally liquid olefins and in some instances alsocontaining substantial amounts of dissolved normally gaseous olefins.

When the reaction is conducted with the olefin in the gaseous phase, theproduct is relatively highly concentrated with respect to the effectiveanti-oxidant material (alkyl-phenols) and may not require distillationor concentration for the purpose of isolating the latter. On the otherhand, when the reaction is conducted with the olefinic material inliquid phase, and especially when the concentration of olefins in thestart ing material is comparatively low, the product may be relativelydilute with respect to the efiective anti-oxidant material, comprisingfor example a solution of such anti-oxidant in gasolinelike polymers orunreacted liquid hydrocarbons. In such case, the anti-oxidant materialmay be concentrated by distillation or otherwise as set forth in theabove-mentioned co-pending applications, prior to being converted intodiaryl ethers by the method described herein.

The exact chemical and structural natures of the anti-oxidant materials,as thus prepared and employed as a starting material in the manufactureof our improved addition agents, is largely obscure. Although we havebeen able to identify certain types of compounds in these anti-oxidantmaterials, it will be realized that, especially since mixtures ofvarious phenols and mixtures of various olefins are frequently employedin the manufacture of these anti-oxidants, the number of possiblechemical compounds is large and varied. In general, they difier from thesimple alkylated phenols in that they are insoluble in dilute causticsoda solution (15% solutions), and also in that they are goodantioxidants and gum-inhibitors, whereas simple alkylated phenols (suchas cresol and xylenol) are not. In general, also, the alkylations, insuch instances as they occur, are of secondary and tertiary types; themethods set forth in the above co-pending applications of Stevens andGruse and of Troy Lee Cantrell, do not produce normal or primaryalkylated linkages. The

those applications and which contain secondary 1 and tertiary alkylgroups, are converted by the methods of our co-pending application Ser.No. 138,858 into substituted diaryl ethers which are advantageous in thepresent invention for improving mineral lubricating oils or likelubricants.

However, diaryl ethers useful in the present invention may also beobtained by the methods of our application Ser. No. 138,858 fromalkylated phenols with normal or primary linkages. While those alkylatedphenols are not themselves good antioxidants or gum inhibitors incracked gasolines and themselves are undesirable for addition to mineraloils, due to the fact that both such materials (alkylated phenols ofboth primary and normal linkages) tend to be insoluble in thehigh-gravity lubricating oils, the alkylated phenyl ethers of2:4-dinitr0benzene obtained from them are readilysoluble in minerallubricating oils and improve the lubricating properties of such oils.

Further, it is possible that certain alkylated phenols of normal orprimary linkage might be satisfactory for addition to high-gravitylubricating oils,- provided the alkyl chains were long enough, saychains of four carbon atoms or more, on account of the closerresemblancein structure of such compounds to paraffinic lubricating oilconstituents. As disclosed in our co-pending application Ser. No.138,858, such long chain alkylated phenols may be converted into usefuldiaryl ethers by the methods described therein. Those diaryl ethers, arealso useful in the present invention. However, the diaryl ethersobtained from the alkylated phenols which are insoluble in dilutecaustic soda. solution and which are good antioxidants or guminhibitors, are very effective improvement agents for minerallubricating oils and we find such alkylated phenolsto be advantageousfor preparing the diaryl ethers used in the practice of the present in'-vention.

We have identified constituents in the various anti-oxidant materialsprepared as set forth hereinbefore, such compounds as follows:

Ortho-isopropyl phenol Ortho-tertiary butyl phenol 2 4-di-tertiary butylphenol Ortho-isoamyl phenol Ortho-tertiary amyl phenol wherein Yrepresents hydrogen or an alkyl group, R is an aliphatic radical and R1,R2 and R3 represent hydrogen or an alkyl group. Such substituted diarylethers may be readily obtained from the correspondingly substitutedalkyl-phenols and 2 4-dinitrochlorobenzene.

As illustrative of the above advantageous class of substituted diarylethers, we may mention the following ethers which have therepresentative structural formulae:

The ortho-isoamyl-phenyl ether of 2:4-dinitrobenzene,

I OQN H H Hts The ortho-tertiary amyl-phenyl ethers of 2:4-dinitrobenzene,

OzN 0 The ortho-tertiary butyl-phenyl ether of 2:4- dinitrobenzene,

cm mc-e-cm The 2:4-tertiary butyl phenyl ether of 2:4- dinitrobenzene,

The'ortho-isopropyl-phenyl ethers of 2:4-dinitrobenzene,

As stated ante, mixtures of the above diaryl ethers may be employed.Also, various mixed ethers containing. the above compounds may be usedto advantage. In general, We have found that substituted diaryl ethersor mixtures of them, having the following properties, yield valuableimproved lubricants according to this invention.

Gravity: API 15 to 25 Viscosity, SUV: 100 F 150 to solid Color "waterwhite to 7 NPA Pour: F. (liquidonly) 0to 30 Melting point: F. (solidonly) 80 to 265 Generally, the diaryl ethers here employed; are readilymiscible and'compatible with petroleum oils in the percentages necessaryfor the present purposes. They may be incorporated with the mineral oilor lubricating base in any suitable manner. ey may be dissolved in the,oil by simply mixing the diaryl ether with the oil and slightly warmingwith agitation to obtain uniform lubricants. Warming to temperaturesbetween F. and 180 F. is usually sufficient; the ethers being readilysoluble. With the heavier and more viscous lubricating oils this warmingis advantageous since the heating lowers the viscosity of the oilfacilitating the blending.

In some cases, the ethers may be dissolved in suitable volatile solventsand the solution added to the oil, the solvent being subsequentlydistilled off. This solvent method is particularly aisaaae,

effective with the solid diaryl ethers. Also, the diaryl ethers may befirst dissolved in a suitable lubricatingoil to form a master batchwhich is subsequently blended with more lubricating oil to give a rangeof lubricating compositions as desired. Likewise, the compoundedlubricant may be converted into thickened compositions or greases in anyof the usual ways. Sometimes the diaryl ether may be directly added tometal soap greases or other compounded lubricants in which a petroleumoil is the lubricating base.

In the practice of the present invention any suitable lubricating oilbase may be employed. Ordinarily it is best to select a good grade oflubricating oil which has suitable initial properties for thelubrication required. Then the addi tion of the substituted diarylethers produces the additional characteristics desired, such as thenecessary extreme pressure qualities, etc.

That is, petroleum oils and lubricants of the usual grades may beemployed in this invention. The oils falling within the well known SAEclasses are among those which can be advantageously improved by ourinvention. Likewise, special lubricants such as obtained by blendingcertain non-petroleum oils with mineral oil may be improved by theaddition of these substituted diaryl ethers.

\ In evaluating the improvement in extreme pressure characteristicsobtained by the addition of these substituted diaryl ethers to variouslubricants, they may be tested by any of the usual methods fordetermining the extreme pressure characteristics of a lubricant. Forinstance, the improved lubricants may be subjected to the Almen test andbycomparison with the original oil in a like test, the necessaryadditionof diaryl .ethers to obtain the desired low bearing qualities can bereadily determined for a given lubricant.

The following examples are illustrative of certain typical embodimentsof this invention:

Example 1 Into a suitable vessel there are introduced 1000 gallons(7341-lbs.) of Pennsylvania motor oil SAE 60 grade and the oil warmed toF. Then 73 pounds of a mixture of substituted diaryl -ethers having thefollowing properties:

Gravity: B. 60 F 14.4 Viscosity, SUV 100 F. (seconds) 143.0 Pour: F. 10

are gradually added and the mixture agitated until a uniform blend isobtained; about 1 hour usually being required. The improved motor oil isthen cooled and is a finished product.

In agitating the mixture, ordinary mechanical agitators may be employedor a current of air may be passed through the warm mixture, to produceuniform blending.

The properties of the original and improved motor oil are as follows:

From the above table, clearly the addition of the a minor proportion ofa substituted di-aryl ether substituted diaryl ether does notsubstantially change the ordinary properties of the oil. However, theimproved lubricant obtained is a satisfactory extreme pressurelubricant.

When tested by the Almen test, the following results were obtained:

From the above results, the beneficial effect of the mixture ofsubstituted diaryl ethers as an improvement agent for the oil is quiteapparent.

The mixture of substituted diaryl ethers employed in the above examplewas prepared according to Example 4 of Serial No. 138,858.

By employing the same blending procedure as in the above example butsubstituting other motor oils, those motor oils may be likewiseimproved. Also, in the above examples, other mixtures of substituteddiaryl ethers may be used in lieu of the particular mixture given andthe same improvements obtained. Again, any one of the particularsubstituted diaryl ethers mentioned ante may be employed instead of amixture of such ethers.

The above example and specific compounds mentioned herein areillustrative embodiments of the present invention. That is, thepercentage of diaryl ethers employed may be varied as indicated,according to the particular properties desired in the final lubricant.Likewise, the lubricating base desired may be selected according to thelubricant to be produced. For instance,

any of the usual greases or mixtures of mineral oils and non-mineraloils, may be used in making lubricants of our improved type. In making'these improved lubricants, various diaryl ethers may be used toparticular advantage. These subclasses of diaryl ethers have beenpointed out ante. For instance, those containing an alkyl group havingone or more branched chains, such as iso-propyl, tertiary-butyl,isoamyl, etc., may be advantageously employed in the present inventionbecause of their effectiveness and marked solubility in minerallubricating oils. Also, the polyalkylated diaryl ethers have advantage.In these, the multiplicity of alkyl groups likewise improves the oilsolubility of the diaryl ethers. Further. with one or more alkyl groupsin the ortho position, the aryl ethers seemingly are sensitized withrespect to their ability to impart extreme pressure characteristics tothese lubricants.

What we claim is:

1. As a composition of matter, an improved lubricant containing a majorproportion of mineral lubricating oil and minor proportion of analkyl-phenyl oxy-ether of 2:4-dinitro benzene.

2. The composition of claim 1 wherein said ether is anortho-alkyl-phenyl ether.

3. The composition of claim 1 wherein said ether is a polyalkyl-phenylether.

4. As a composition of matter, an improved lubricant comprising minerallubricating oil and having the following formula:

R3 wherein Y represents a substituent of the .class consisting ofhydrogen and an alkyl group, and R1, R2 and R4 represent a substituentof the class consisting of hydrogen and an alkyl group, at least one ofthe substituents represented by R1, R2 and R3 being an alkyl group,suflicient of .diaryl ether being present to impart extreme pressurecharacteristics to said mineral oil.

5. The improved lubricant of claim 1 wherein said alkyl-phenyl ethercontains at least one branched chain alkyl group attached to said phenylgroup.

6. As a composition of matter, an improved lubricant comprising, a majorproportion of mineral lubricating oil and a minor proportion.

of an alkyl-phenyl oxy-ether having the following formula:

wherein Y1 represents a substituent of the class consisting of hydrogenand a butyl group.

11. The composition of claim 6 wherein said alkyl-phenyl ether is the2-tertiary-butyl-phenyl oxy-ether of 2:4-dinitrobenzene.

12. The composition of claim 6 wherein said alkyl-phenyl ether is the2-isopropyl-phenyl oxyether of 2:4'-dinitrobenzene.

13. The compdsition of claim 6 wherein said alkyl-phenyl ether is adi-substituted diaryl ether having the formula:

I501 molt-cm wherein X is a substituent of the class consisting ofhydrogen, CH3 and CzHs.

14. The composition of claim 6 wherein said alkyl-phenyl ether is the2-tertiary-amyl-phenyl oxy-ether of 2':4'-dinitrobenzene.

TROY LEE CANTRELL. JAMES OTHO TURNER.

